Re: 9 bit communication on RS 232

"Tilmann Reh" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> suchitra schrieb:
>
> > I wanted to know how can we configure com port for 9 bit
> > communication.
> > I intend to use the 9th bit as Address/data bit..since i want to
> > communicate with more than one devices.
> > I am using turbo c compailer if some one can give me some reference
> > code that will be great..
>
> While most, if not all, embedded controllers have this ability
> with their UARTs, I fear that the standard PC COM port has not...
>

There is the 9th bit on 8250-style chips, although the standard COM port
drivers do not understand to use it. It's the 'stick parity' bit which can
be used with 8-bit data length.

If you are not forced to use the ninth bit, you may be better off by
encapsulating the data in PPP-like frames, which are binary-transparent with
plain old 8-bit data transfer channel.

For details, get RFC 1662.

HTH

Tauno Voipio
tauno voipio @ iki fi